"Thanks GoHawks. I took the car to the dealership and the diagnostic test was P0304=Cylinder 4 Misfire. They did reflash the PCM and the problem seemed to have been resolved with the flash. I asked them if this was simply software or if it was hardware related. They said software only but now you've got me wondering if they even checked anything on the engine."

jjm86m...This is your post from your other thread. Your car originally coded P0304. Did you remind them of that? The wrong PCM program will not cause a misfire without there being something wrong with that cylinder. This should have been enough for them to look under the valve cover.

The voucher is expressly to cover the work of removing the valve cover. It was never meant to be for any other purpose. I'm well aware that someone is covering the cost and that the dealership isn't going to do the work for free.

My point with the comment "this probably isn't the way things are supposed to work" was simply voicing frustration over the fact that if there is no code or no noise then there is apparently no problem. This is in spite of the fact that in this case I have documentation that there was an previous issue specific to my car and an associated TSB that outlined instructions to inspect the car that wasn't followed the first time around. I've read on this thread that people can't believe that the dealership doesn't know about certain TSB's. To a certain extent that may be true that techs need to be informed but in reality dealerships are servicing many Mazda models from across multiple years. To expect the service team to know each and everyone offhand for all makes/models/years is unrealistic but I would expect that they at least put a little more effort into investigating the problems that customers bring in.

The bottom line is that the dealership was in a no win situation where Mazda wasn't going to pay for the work based on their corporate technician's assessment and I wasn't willing to pay out of pocket on something I felt should be covered under the powertrain warranty. Mazda Customer Service was quick to provide a solution in the form of a voucher after I raised the issue as a safety concern and explained the situation. Kudos to them.

Today's update is that the dealer pulled the valve cover and found there is an issue with the cylinder #4 "lifter arm". I asked for clarification on rocker arm vs lifter arm and it sounded to be the same thing. Mazda Corporate has asked for pictures and videos from the dealership and will provide input to the dealership on next steps. Stay tuned.

The voucher is expressly to cover the work of removing the valve cover. It was never meant to be for any other purpose. I'm well aware that someone is covering the cost and that the dealership isn't going to do the work for free.

My point with the comment "this probably isn't the way things are supposed to work" was simply voicing frustration over the fact that if there is no code or no noise then there is apparently no problem. This is in spite of the fact that in this case I have documentation that there was an previous issue specific to my car and an associated TSB that outlined instructions to inspect the car that wasn't followed the first time around. I've read on this thread that people can't believe that the dealership doesn't know about certain TSB's. To a certain extent that may be true that techs need to be informed but in reality dealerships are servicing many Mazda models from across multiple years. To expect the service team to know each and everyone offhand for all makes/models/years is unrealistic but I would expect that they at least put a little more effort into investigating the problems that customers bring in.

The bottom line is that the dealership was in a no win situation where Mazda wasn't going to pay for the work based on their corporate technician's assessment and I wasn't willing to pay out of pocket on something I felt should be covered under the powertrain warranty. Mazda Customer Service was quick to provide a solution in the form of a voucher after I raised the issue as a safety concern and explained the situation. Kudos to them.

Today's update is that the dealer pulled the valve cover and found there is an issue with the cylinder #4 "lifter arm". I asked for clarification on rocker arm vs lifter arm and it sounded to be the same thing. Mazda Corporate has asked for pictures and videos from the dealership and will provide input to the dealership on next steps. Stay tuned.

Wow, just as Go Hawks predicted. I hope that they share the pictures with you so we can see what it looks like. Also see what they say caused it, if they have the same explanation that they gave Go Hawks or if they have a different reason why it broke.

Dangerous cylinder deactivation trouble on 2018 CX-5 and 6 models

Originally Posted by jjm86m

* Today's update is that the dealer pulled the valve cover and found there is an issue with the cylinder #4 "lifter arm". I asked for clarification on rocker arm vs lifter arm and it sounded to be the same thing. Mazda Corporate has asked for pictures and videos from the dealership and will provide input to the dealership on next steps. Stay tuned.

Yes rocker arm is the lifter arm. I really feel this's a very strange experience for you as Mazda has officially sent a service alert to NHTSA, that means Mazda North American Operations have also sent the same alert to all of their dealers. It does instruct the dealer to open the valve cove and check the rocker arm at cylinder #4 if the engine fell into the limp mode when it revs at high rpm and got the misfire code on cylinder #4. I wonder why the Mazda dealer can't follow the service alert to do it and get paid by Mazda? The gift card thing for you to pay the cost of inspection of rocker arm is ridiculous to me.

Glad now you found the real issue and I wonder are you going to get a "new" engine, or the tech just put the rocker arm back to the position?

Although you're the first to report this issue, but nobody would know what's going on here at the time. Not until Go Hawks the OP came out and posted his research and experience on such weird issue, we realized Mazda made a big design mistake on cylinder deactivation and every SkyActiv-G 2.5L with CD would potentially have its rocker arm falling off on cylinders with CD. We should appreciate Go Hawks who started this thread, although some here was questioning he was spreading fake news.

Lastly, I don't believe a software change with higher oil pressure to Hydraulic Lash Adjuster or Hydraulic Lifter during the CD phase can truly resolve this problem. The HLA's for cylinder #1 and #4 need to be redesigned in such a way that even at the lowest oil pressure, it won't be too low and let the rocker arm fall off. Or some holder needs to be added to keep the rocker arms at the bay hence even the HLA's are at their lowest or shortest the rocker arms would stay put.

Thanks yrwei52. Now jjm86m is in the same boat as we are. The car is fixed and, in our case, has a new engine but we still donít feel secure. Because, like you, we are not sure that we buy Mazdaís explanation of the cause. And, since there is no indication of the problem existing until its too late, my wife is a nervous wreck any time a bell dings or an alarm sounds while she is in the car. So, we are forced to drive this until we can get through with the lease and then move on from Mazda. Mind you, this is our third Mazda but most likely will be our last.

For those who were asking, I was able to take a few pictures of what the rocker arm looks like when its fallen off. I stopped by the dealership to grab a few things from my car and talked with the technician for a bit. He was a lot more helpful than the service rep and showed me all the paper work he got and said the copy of the work showing that I had a P0304 previously never got to him. WTH! For those that are going ask how he didn't have the record, Hindsight is 20/20 I should've taken my car back to the same dealership that did the P0304 code work for me. The first dealership I took it too was the one I purchased the car from and I was having an oil change done that day as part of the year free service and 80 miles from my work/home. The second trip I ended up taking it to the dealership 10 miles from my place to avoid having to take off more time off from work than necessary.

Anyways, while I was there I asked to grab a few pics and was able to get the ones below.

I'm also grabbed a shot of the service bulletin with the instructions to check for the rocker arm from Mazda. The SA-015/19 posted earlier in this thread is for checking debris but SA-041/18 is the specifically for the rocker arm. Inspection step 3 is important for anyone owning a Mazda that may be affected. Make sure your oil change service records are verifiable, especially if you're doing your own oil changes. I wouldn't put it past a dealership to hassle you over something like that. They didn't for me but you never know.

Yes rocker arm is the lifter arm. I really feel this's a very strange experience for you as Mazda has officially sent a service alert to NHTSA, that means Mazda North American Operations have also sent the same alert to all of their dealers. It does instruct the dealer to open the valve cove and check the rocker arm at cylinder #4 if the engine fell into the limp mode when it revs at high rpm and got the misfire code on cylinder #4. I wonder why the Mazda dealer can't follow the service alert to do it and get paid by Mazda? The gift card thing for you to pay the cost of inspection of rocker arm is ridiculous to me.

Glad now you found the real issue and I wonder are you going to get a "new" engine, or the tech just put the rocker arm back to the position?

Although you're the first to report this issue, but nobody would know what's going on here at the time. Not until Go Hawks the OP came out and posted his research and experience on such weird issue, we realized Mazda made a big design mistake on cylinder deactivation and every SkyActiv-G 2.5L with CD would potentially have its rocker arm falling off on cylinders with CD. We should appreciate Go Hawks who started this thread, although some here was questioning he was spreading fake news.

Lastly, I don't believe a software change with higher oil pressure to Hydraulic Lash Adjuster or Hydraulic Lifter during the CD phase can truly resolve this problem. The HLA's for cylinder #1 and #4 need to be redesigned in such a way that even at the lowest oil pressure, it won't be too low and let the rocker arm fall off. Or some holder needs to be added to keep the rocker arms at the bay hence even the HLA's are at their lowest or shortest the rocker arms would stay put.

And according to the procedure it looks like engine replacement is their answer, gonna be an expensive fix!

Dangerous cylinder deactivation trouble on 2018 CX-5 and 6 models

Originally Posted by jjm86m

For those who were asking, I was able to take a few pictures of what the rocker arm looks like when its fallen off. I stopped by the dealership to grab a few things from my car and talked with the technician for a bit. He was a lot more helpful than the service rep and showed me all the paper work he got and said the copy of the work showing that I had a P0304 previously never got to him. WTH! For those that are going ask how he didn't have the record, Hindsight is 20/20 I should've taken my car back to the same dealership that did the P0304 code work for me. The first dealership I took it too was the one I purchased the car from and I was having an oil change done that day as part of the year free service and 80 miles from my work/home. The second trip I ended up taking it to the dealership 10 miles from my place to avoid having to take off more time off from work than necessary.

Anyways, while I was there I asked to grab a few pics and was able to get the ones below.

I'm also grabbed a shot of the service bulletin with the instructions to check for the rocker arm from Mazda. The SA-015/19 posted earlier in this thread is for checking debris but SA-041/18 is the specifically for the rocker arm. Inspection step 3 is important for anyone owning a Mazda that may be affected. Make sure your oil change service records are verifiable, especially if you're doing your own oil changes. I wouldn't put it past a dealership to hassle you over something like that. They didn't for me but you never know.

Thanks to your extra effort to get more information out of this rocker arm falling off problem! Getting some pictures with another related service alert is much appreciated as a picture is worth a thousand words!

Are you going to get a new or factory-rebuilt engine? If Mazda can't tell you what fixes have been done on the new or rebuilt engine, how can they know the same problem won't happen again?

Service Alert SA-015/19 Mazda submitted to NHTSA is actually related Service Alert SA-041/18 you posted.

Originally Posted by Mazda Service Alert SA-015/19

Subject: CHECK ENGINE LIGHT COMES ON WHEN DRIVING WITH P3400 STORED IN PCM

Service Alert No.: SA-015/19Last Issued: 04/08/2019

APPLICABLE MODEL(S)/VINS

2018 Mazda6
2018-2019 CX-5
2019 Mazda3

DESCRIPTION

If you receive a customer concern with the check engine light coming on and DTC P3400 (cylinder deactivation system malfunction) stored, perform the inspection in the Repair Procedure.

REPAIR PROCEDURE

1. Remove the valve cover and inspect for any rocker arms that are broken or have fallen off, especially in the cylinder deactivation area (cylinders 1 and 4). Refer to SA-041/18 if found.
Ö